Eddie, We have an ADS131E04EVM and I had to test out the device to see what it does at start up. When I plug it in to start up, it does start with the /DRDY high. When in operation, the /DRDY will spend most of the time high because it follows the /CS high after configuation and reading the device. When I look at the EVM /DRDY, the device comes up active. There is already a periodic /DRDY indication. For each one of these /DRDY transitions low, the EVM responds by sending a null command, and the device responds with an FF04 (for your device, you would get the FF02). If there hasn't been a setup, then it means the device comes up active. Then for the EVM, I still need to do an UNLOCK, WAKEUP, and then WREG for 0F 0F to enable the ADCs. For your setup, it does seem like the oscilloscope plot is inverted. However, you might get the same thing if you left the /CS low after sending the first commands. The /DRDY would appear as pulses and idle low. I'll look through your setup and ask a couple of engineers that have a bit more experience with this particular device and I'll get back to you. Joseph Wu
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